An osteoporosis drug called strontium ranelate (brand name Protelos) could become the first drug to actually slow the progression of osteoarthritis, scientists have found.

Strontium ranelate is already approved in the UK for the treatment of the bone-thinning disease osteoporosis in postmenopausal women.

Now, research presented at the European Congress on Osteoporosis and Osteoarthritis suggests that the drug - which costs less than £1 per day - may delay the advance of osteoarthritis, as well as reducing pain and improving mobility in patients with the degenerative joint disease.

The phase-III study involved 1,683 men and women, all of whom were aged 50 or above and had been diagnosed with osteoarthritis of the knee.

Participants were given one of two oral doses of strontium ranelate (1g or 2g per day) or a placebo (dummy treatment) for three years.

The researchers found that patients who took strontium ranelate typically exhibited around a third less cartilage degradation than those who took the placebo.

For every three years of treatment, disease progression slowed by one year.

The researchers also observed that strontium ranelate was associated with a reduction in pain and improved mobility.

Lead investigator Professor Cyrus Cooper, professor of rheumatology at the University of Southampton and professor of musculoskeletal science at Oxford University, described the findings as a "major breakthrough".

He revealed: "Osteoarthritis is a painful and debilitating condition, and for over 20 years we have been searching for a treatment that would allow us to alter the course of the disease, rather than just manage the symptoms.

"The results today are it, and could totally change the way we treat osteoarthritis. For the first time we have a treatment that can slow the development of this debilitating disease and could reduce or even eliminate the need for expensive and painful joint replacement surgery."

Medical director of Arthritis Research UK, Professor Alan Silman, said the result of the phase III trial was an “exciting development” and showed that strontium ranelate could be valuable in treating osteoarthritis.

“This the first time that a drug has been shown to slow progression of osteoarthritis, as existing treatments focus on symptoms.

“Although it doesn’t reverse osteoarthritis it slows down its progression as seen in x-rays, and appears to have a beneficial effect on pain, although the extent of this is unclear.”

This news will give hope to the millions of people living with osteoarthritis. However, it is important to note that the drug will not be available for patients immediately.

Before the drug can be made available for use as an osteoarthritis drug, there are several stages it must go through. The research still needs to be published and then the drug must be licensed by the MHRA and EMEA for use as an osteoarthritis drug. It will then need NICE approval before it can be made available to patients on the NHS.

It is difficult to say how long this process will take, however it is unlikely that these drugs will be available to patients in the immediate future.

For more information, go to www.arthritisresearchuk.org.Arthritis Research UK fund research into the cause, treatment and cure of arthritis. You can support Arthritis Research UK by volunteering, donating or visiting our shops.